1. Field of the Invention
The present invention relates generally to telephone handsets and, more particularly, to a system and method for sealing around openings in a telephone handset casing in which externally facing components are positioned, such as liquid crystal displays, audio receivers, and audio speakers.
2. Background of the Invention
Modern telephone handsets, such as cordless telephones and cellular telephones, are typically constructed of an outer plastic or metal casing having openings in which various externally facing components are positioned. Such components include, for example, liquid crystal displays (LCDs), audio speakers, and audio receivers. A component is positioned in an opening of the telephone handset casing, sometimes under a transparent cover. The gap between the frame of the opening and the component is preferably sealed to prevent dust and moisture from entering the space between the component and the transparent cover, which could obscure or hinder the operation of the component. For example, if the component is an LCD, the presence of dust, dirt, or other particles can detract from the quality of the display.
To seal the gap between the frame of the opening and the component, a conventional approach has been to apply a foam gasket to the frame of the opening. Pressure sensitive adhesive on one side of the foam gasket holds the gasket to the casing around the perimeter of the opening. The externally facing component presses against this foam gasket to provide the seal.
FIGS. 1A-1C illustrate a conventional foam gasket 102 applied to the inside front half of a telephone handset casing 104, to provide a seal between the casing 104 and an LCD (not shown). In applying the gasket 102, an assembly worker removes the foam gasket 102 from its paper backing 106 as shown in FIG. 1B, thereby exposing the pressure sensitive adhesive on the underside of the gasket 102. Then, the worker manually positions the gasket 102 over the opening 108 in the casing, taking care to properly position and align the gasket 102 with the opening 108. Depending on the skill of the worker, the gasket 102 can often be misaligned and partially extending into the opening 108, which can obscure a portion of the LCD, compromise the aesthetics of the telephone handset, and prevent an adequate seal between the LCD and the casing. The pressure sensitive adhesive can also frustrate attempts to remove and re-position the foam gasket without damaging it. The manual process of removing and carefully applying the gasket is also time-consuming. In addition, the foam gaskets are typically die-cut out of full sheets of foam, which creates considerable foam product waste in the areas within and between the foam gaskets, as shown in FIG. 2.
Thus, there remains a need for a system and method for adequately sealing components to openings in a telephone handset casing.